The present invention relates generally to fiber optic needle probes adapted for use in optical imaging systems.
Optical imaging systems such as optical coherence tomography (OCT) systems generate images or measurements by measuring the intensity of light backscattered or backreflected from a specimen and providing a gray scale or false color two-dimensional representation of this light intensity in a plane or cross-section through the object being imaged or measured. OCT enables the nonexcisional, in situ, real-time imaging of microstructure in a specimen with a resolution of approximately 2 to 10 microns.
An OCT system can be separated into an imaging engine and probes. The imaging engine contains the optical light source, optical interferometer and other optical detection elements, as well as electronics, motors, controller(s), and computers for image generation and display. The probes are modules which are attached to the engine and direct light to and from the specimen which is to be measured or imaged.
In spite of advances in probe construction and in related delivery and scanning techniques, all previous OCT systems have had the major limitation of being applicable only for imaging internal structures which are accessible from existing orifices of the body or intraluminally from inside a hollow organ. There remains a critical, unfilled need for a new apparatus which enables optical coherence tomographic imaging inside solid tissues or organs without the need for intraluminal insertion.
The present invention provides a fiber optic needle probe adapted for use in an optical imaging system, particularly for use in imaging solid tissues and organs. In biological and medical applications, the fiber optic needle probe can be inserted directly into a solid tissue or organ or through a tissue wall into the lumen of a hollow organ or space (such as into a sinus cavity or into a blood vessel). The fiber optic needle probe can be inserted with minimal trauma into a tissue because of its small diameter. Thus, the fiber optic needle probe of the present invention enables optical measurement and imaging in regions of the body which are not accessible using existing catheter, endoscope, or laparoscope technology.
In one embodiment of the invention, the fiber optic needle probe comprises a needle having a tip and a wall defining a bore. The needle is sized and shaped for nonintraluminal insertion into a specimen. At least a portion of an optical fiber is positioned within the bore of the needle. In a first embodiment, the optical fiber is independently movable within the needle. In a second embodiment, the optical fiber and needle comprise a single, integrated unit, i.e., the optical fiber is fixedly positioned within the needle and the needle and optical fiber move as one. A beam director is positioned in close juxtaposition to, the first end of the optical fiber to direct light from the optical fiber to the specimen being imaged. In a further embodiment of the invention, the wall of the needle comprises an optical port. In this embodiment of the invention, the beam director is positioned in close juxtaposition to the optical port and is capable or directing light and receiving light through the optical port. The port may be configured to permit transmission of light along a plurality of points substantially linear with a longitudinal axis of the needle. In another embodiment, the port is configured to permit transmission of light over a range of positions orthogonal to a longitudinal axis of the needle.
In another embodiment of the invention, the fiber optic needle probe needle comprises a coring tube positioned within the bore of the needle. In this embodiment of the invention, the optical fiber is positioned substantially within the coring tube (as used herein, xe2x80x9cpositioned substantiallyxe2x80x9d means that greater than 50% of the length of the optical fiber is positioned within the coring tube). Optical elements comprising the beam director are positioned in close juxtaposition to the optical fiber and may be integral with the fiber or separate from the fiber.
In a further embodiment of the invention, the fiber optical needle probe comprises a two-channel needle assembly. The two-channel needle assembly comprises a first housing and a second housing defining a first and second channel, respectively. An optical fiber is positioned substantially within the lumen or channel of the second housing and is in optical communication with a beam director. The second housing is constructed of a rigid or semiflexible material capable of emitting a single mode optical beam and receiving backscattered or backreflected light from the sample. The second housing is positioned in close juxtaposition to the first housing and the entire assembly of the first housing and the second housing has a small outer diameter allowing the assembly to be inserted directly into tissues or specimens. The first and second housing are sized and shaped for nonintraluminal insertion into a specimen. In a further embodiment of the invention, the first housing comprises an extracting device (e.g., a cutting device, a coring device, an aspirating device or a pinching device). In one embodiment, the two-channel needle assembly is used as a biopsy needle with imaging capabilities.
The fiber optic needle probe can be used in conjunction with a number of different types of optical imaging systems, in particular, with systems which deliver and collect a single spatial mode optical beam. There are a variety of OCT imaging systems which are included within the scope of the invention, including those which provide optical path length scanning, tunable optical source scanning, optical source scanning, optical spectrum analysis imaging, and optical phase delay-line scanning. Other interferometric imaging and ranging techniques are also encompassed within the scope of the present invention. OCT is the preferred imaging technology to be used with the fiber optic needle probe described herein because it can perform very high sensitivity and high dynamic range measurements of the echo time delay and intensity of backreflected and backscattered light.
In the preferred embodiment of the invention, the fiber optic needle probe communicates with the imaging engine of an OCT device by means of a single mode optical fiber housed within the needle or, within the second housing, in the case of the two-channel needle assembly. In one embodiment, an actuating device is coupled to the fiber optic needle probe to effect the movement of any of the needle, the optical fiber, the beam director, and combinations thereof. The actuator allows an optical beam directed from an OCT device to be scanned by mechanically scanning the position and/or rotation of any, or all of, the needle, optical fiber, and beam director. In one embodiment of the invention, the actuator is a motor coupled to the wall of the needle and the motor comprises a motor and a coil, with at least one of the magnet and the coil capable of movement. In this embodiment of the invention, at least one of the magnet and the coil is coupled to the optical fiber and capable of causing a scanning motion of the fiber. Used in conjunction with an OCT imaging system, the fiber optic needle probes of the present invention enable the tomographic imaging of the micro-structure of internal organs and tissues which were previously impossible to image in a living subject.
The fiber optic needle probes of the present invention may be used in a variety of applications. In medical diagnostic and imaging applications the fiber optic needle probes may have a range of diameters and may be configured in the form of biopsy needles, hollow acupuncture needles, as part of cannulas, or the like. When the fiber optic needle probes of the present invention are used in conjunction with, or integrated with, biopsy devices, imaging of tissue or organs in proximity to the probe will guide the way the physician performs the biopsy and reduce sampling errors or injury to sensitive tissue structures. Similarly, the fiber optic needle probes of the present invention can be adapted for use in other surgical procedures, for example, in guiding the course of tumor resections.
However, the use of these fiber optic needle probes is not limited to medical diagnostic imaging applications in humans. In further embodiments of the invention, the probes are used for optical measurements (both imaging and nonimaging) in animals and plants. The fiber optic needle probes can also be used for applications which require spatially resolved spectroscopic analysis. In one such application, the fiber optic needle probe is used to deliver optical radiation to a tissue or organ system and to collect scattered radiation from the tissue or organ. Additionally, in another embodiment of the invention, the fiber optic needle probe is used to deliver optical radiation to a tissue, exciting fluorescence in the tissue. The fluorescent light produced by the tissue is then collected by the fiber optic needle probe. In a further embodiment of the invention, the fiber optic needle probes are used in process monitoring of chemical or material synthesis where the device characterizes inhomogeneities in the process using spectroscopic signatures.